Affects the Linux kernel, a core infrastructure used across industries; remote memory disclosure could impact many systems.
CVE-2026-43039
Linux kernel networking path leaks uninitialized heap data to userspace.
Is CVE-2026-43039 being exploited?
Not confirmed. CVE-2026-43039 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.31% probability of exploitation in the next 30 days.
How severe is CVE-2026-43039?
CVE-2026-43039 is rated Critical with a CVSS score of 9.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-43039?
Yes. A fix has been recorded for CVE-2026-43039. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-43039 affect?
CVE-2026-43039 affects Linux kernel. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-43039?
Patch kernel to fixed version; apply distro security patch
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote memory disclosure via crafted packets; kernel heap contents exposed to user space.
Immediate action required
- affected>= 7a64bb388df3cf091afdd047c701039a13acd3b4 and < a968438d4fc17ee1dcdc3cfa490dcb5e7709cf76
- affected>= 7a64bb388df3cf091afdd047c701039a13acd3b4 and < 5597dd284ff8c556c0b00f6a34473677426e3f81
- affected6.19
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.